Silicon nitride films are known and are being used in a wide variety of applications including, for example, the fabrication of electronic circuits and devices, as well as to provide surface protection and/or passivation for electronic devices and other materials. Silicon nitride films may be formed by Chemical Vapor Deposition (CVD) processes using, for example, as source gases, dichlorosilane (SiCl2H2) and ammonia (NH3). Chemical Vapor Deposition (CVD) is a process whereby a solid material is deposited from a vapor by a chemical reaction that occurs on or nearby a heated substrate. The solid material is obtained as a coating, a powder, or as single crystals.
One problem with known methods for forming silicon nitride films relates to poor conformal or “step” coverage on substrates containing small features. While such poor conformal coverage is generally undesirable, it usually has been not been a problem for the relatively large scales (i.e., sizes) of electronic circuits and devices fabricated to date. However, the ability to fabricate ever small circuits and devices, such as those associated with ultra-large scale integrated (ULSI) circuitry, is beginning to be hampered by the limited ability of known deposition methods to provide sufficiently conformal silicon nitride coatings. Stated another way, the inability to form sufficiently conformal silicon nitride coatings is beginning to be an impediment to the development of smaller and/or higher density circuit devices and elements.